DE69116737T2 - Conditioning sheet for fabric dryers, containing compatible silicones - Google Patents

Description

HISTORY OF THE INVENTION FIELD OF INVENTION

The present invention relates to the application of adjuvants to fabrics in tumble dryers. More particularly, it relates to an article in the form of a flexible substrate carrying a fabric conditioning composition.

RELATED AREAS

Silicones have been applied to fabrics during fabric manufacture or during processing into articles of clothing. With respect to the application of silicones to fabrics during a laundering process, GB-A-1 549 480; Burmeister et al., US-A-4 818 242; Konig et al., US-A-4 724 089; Konig et al., US-A-4 806 255; Dekker et al., US-A-4 661 267 and Trinh et al., US-A-4 661 269 describe aqueous dispersions or emulsions of certain limited viscosity silicones incorporated in the liquid rinse cycle of fabric softening compositions. A fabric softening composition containing emulsified silicone is also taught by Barrat et al. in US-A-4 446 033. Coffindafer et al., in US-A-4 800 026, describes fabric care compositions containing curable amine-functional silicones.

The application of fabric softeners to fabrics in the tumble dryer by using a flexible substrate carrying the fabric softeners is known to those skilled in the art. The advantages of fabric conditioning agents added to the dryer include more convenient addition time in the washing process and the avoidance of undesirable interaction of softeners with detergents.

Rudy et al., U.S. Patent No. 3,972,131, describes dryer sheets containing a silicone oil as an ironing aid. Kasprzak et al., U.S. Patent No. 4,767,548, describes the use of certain silicones in dryer sheet formulations. Coffindafer et al., U.S. Patent No. 4,800,026, describes curable amine-functional silicones in fabric care compositions.

In the manufacture of the dryer-added fabric conditioning sheets described in the above-mentioned references, the resulting mixtures are non-homogeneous and phase separation occurs very easily when silicones are mixed with fabric softeners. The homogeneity of such mixtures is only ensured by continuous vigorous agitation. An additional problem associated with the use of a non-homogeneous mixture is the separation of actives at the time of application of the active mixture to the substrate, resulting in unevenly impregnated sheets.

The compositions described in the prior art contain individual particles of a silicone and individual particles of a fabric softening agent.

In the present invention, the dispersed particle is a composite particle containing a mutually compatible mixture of a silicone and a fabric softening component. Compatible organosilicones described herein preferably form mutually soluble mixtures with certain types of commonly used fabric softening agents. Critically, the organosilicones in the dispersed composite particles do not separate from the fabric softening agents during processing, standing, coating or drying of the dryer sheet. An additional advantage provided by the present invention is simplified preparation of fabric softener compositions since the silicones do not have to be dispersed separately and can be introduced into the composition simultaneously with a fabric softener.

Another advantage of using compatible silicones is that compatible silicones increase the spread of the fabric softening agents on the fabric surface as compared to the spread of the fabric softening agents alone or in combination with incompatible silicones. As a result of using compatible silicones as described herein, more complete surface coverage by a fabric softening agent is achieved with a further advantage of lower dosage requirements. In addition, a smooth and even distribution of the active compounds on the dryer sheet can be achieved, reducing the problem of unevenly impregnated sheets.

Accordingly, it is an object of the invention to provide an article which provides for the release of a fabric conditioning composition within an automatic clothes dryer, the composition containing a compatible blend of a fabric softening component and a selected organosilicone.

These and other objects and advantages of the invention will be explained in the following description.

SUMMARY OF THE INVENTION

The present invention is based in part on the discovery that specific silicones, defined herein as compatible, are capable of forming compatible blends with certain conventional fabric softening agents.

It is important to distinguish between compatible and incompatible silicones and between mutually soluble and insoluble Mixtures of silicones and fabric softeners. Compatibility as described herein is critical and is determined by the appearance of the mixture of a silicone and a fabric softener. When a silicone and a fabric softener are heated and mixed together, the resulting liquid mixtures are either transparent or opaque. In the transparent mixtures, the silicone and fabric softener are mutually soluble and thus suitable for use in the present invention. In the opaque mixtures, the silicone and fabric softener are mutually insoluble and the mixtures may or may not form mutually stable dispersions. A mutually stable dispersion is also compatible and is formed when a mixture of a silicone and a fabric softener does not separate into more than one phase upon storage at elevated temperatures and when the mixture does not form a uniform solid or liquid upon cooling. Accordingly, the class of compatible mixtures as defined herein includes mutually soluble mixtures as well as mutually stable dispersions. The compatibility of the mixture is crucial and is determined by the Silicone Plasticizer Compatibility Test (SSCT) described below.

In its broadest embodiment, any objectives of the invention are achieved by a liquid fabric conditioning composition which includes from about 1% to about 60% composite particles containing a mutually soluble mixture of a fabric softening component and an organosilicone. Of course, these particles can also be added to a liquid containing other fabric treatment ingredients including, for example, emollients.

In the first place, the invention provides an article comprising a flexible substrate carrying an effective amount of a fabric conditioning composition attached thereto in a manner which provides for release of the conditioning composition within an automatic tumble dryer at dryer operating temperatures.

The fabric softening component used for liquid compositions herein can be any commonly used fabric softening agent which satisfies the above conditions, provided that it must include at least a portion of the cationic quaternary ammonium salts, either used alone or optionally in admixture with other softening agents such as nonionic softeners selected from the group of tertiary amines having at least one C8-30 alkyl chain, esters of polyhydric alcohols, fatty alcohols, ethoxylated fatty alcohols, alkylphenols, ethoxylated alkylphenols, ethoxylated fatty amines, ethoxylated monoglycerides, ethoxylated diglycerides, mineral oils, polyols, carboxylic acids having at least 8 carbon atoms, and mixtures thereof.

The fabric conditioning composition used in the articles of the present invention contains (A) certain fabric softening agents, used singly or in admixture with one another, and (B) an organosilicone having specific structural conditions and a specific CH₂ percent.

Accordingly, according to a first aspect of the present invention, there is provided a fabric conditioning article which provides for the release of a fabric conditioning composition within an automatic clothes dryer at dryer operating temperatures, the article comprising a flexible substrate carrying thereon discrete composite particles consisting of a compatible mixture of

(a) at least 1% of a fabric softening component containing a cationic quaternary ammonium salt, and

(b) an organosilicone of the type defined below.

DETAILED DESCRIPTION OF THE INVENTION

The fabric conditioning composition of the present invention includes a cationic quaternary ammonium salt The counter ion is methyl sulfate or any halide.

Examples of cationic quaternary ammonium salts include, but are not limited to, the following:

1. Acyclic quaternary ammonium salts with at least two C8-30, preferably C12-22 alkyl chains, such as:

Ditallowdimethylammonium chloride, di(hydrogenated tallow)dimethylammonium chloride, distearyldimethylammonium chloride, dicocodimethylammonium chloride and the like,

2. Cyclic quaternary ammonium salts of the imidazolinium type, such as di(hydrogenated tallow)dimethylimidazolinium methylsulfate, 1-ethylenebis(2-tallow-1-methyl)imidazolinium methylsulfate and the like;

3. Diamido-quaternary ammonium salts, such as:

Methyl bis(hydrogenated tallowamidoethyl)-2-hydroethylammonium methylsulfate, methyl bis(tallowamidoethyl)-2-hydroxypropylammonium methylsulfate and the like;

4. Biodegradable quaternary ammonium salts such as N,N-di(talloyl-oxyethyl)-N,N-dimethylammonium chloride and N,N-di(talloyl-oxypropyl)-N,N-dimethylammonium chloride and the like. When fabric conditioning compositions use biodegradable quaternary ammonium salts, the pH of the composition is preferably adjusted to values between about 2 and about 5. Biodegradable quaternary ammonium salts are described, for example, in US-A-4,767,547 and US-A-4,789,491.

5. Mixtures of water-insoluble cationic fabric softeners and polyalkoxylated ammonium salts as described in US-A-4,422,949. Such mixtures are particularly suitable for incorporation in concentrated form of the liquid compositions herein.

The fabric softening component may include fabric softeners other than the cationic quaternary ammonium salts. Additional fabric softeners suitable for use herein may be selected from the following classes of compounds be:

(i) Tertiary fatty amines having at least one and preferably two C8-30, preferably C12-22 alkyl chains. Examples include hardened tallow amine and cyclic amines such as 1-(hydrogenated tallow)amidoethyl-2-(hydrogenated tallow)imidazoline. Cyclic amines which can be used for the compositions herein are described in US-A-4,806,255.

(ii) Carboxylic acids having 8 to 30 carbon atoms and one carboxyl group per molecule. The alkyl portion has 8 to 30, preferably 12 to 22 carbon atoms. The alkyl portion may be linear or branched, saturated or unsaturated, with linear saturated alkyl being preferred. Stearic and myristic acid are preferred fatty acids for use in the composition herein. Examples of these carboxylic acids are commercial grades of stearic acid and the like, which may contain small amounts of other acids.

(iii) Esters of polyhydric alcohols, such as sorbitan esters or glycerol stearate. Sorbitan esters are the condensation products of sorbitol or isosorbitol with fatty acids such as stearic acid. Preferred sorbitan esters are monoalkyl esters. A common example of sorbitan ester is SPAN 60 (ICI), which is a mixture of sorbitan and isosorbide stearates.

(iv) Fatty alcohols, ethoxylated fatty alcohols, alkylphenols, ethoxylated alkylphenols, ethoxylated fatty amines, ethoxylated monoglycerides and ethoxylated diglycerides.

(v) Mineral oils and polyols such as polyethylene glycol.

(vi) condensation products of higher fatty acids with polyamines selected from the group consisting of hydroxyalkylalkylenediamines, dialkylenetriamines and mixtures thereof as described in US-A-4,661,269.

Preferred fabric softeners for use herein are acyclic quaternary ammonium salts, with ditallowdimethylammonium chloride being most preferred for the fabric conditioning compositions of this invention. Particularly preferred are mixtures of ditallowdimethylammonium chloride with fatty acids, especially stearic acid or myristic acid.

Typically, from about 1% to about 40% of the fabric softening component is used in the compositions of the invention. At least a sufficient amount of quaternary ammonium salt must be present to provide an antistatic effect, for example, from about 1% to 3% in the diluted product and from about 2% to about 5% in the concentrated product. Alternatively, all of the fabric softening component may be quaternary ammonium salt. The diluted version of the product contains from about 1% to about 12%, preferably from about 3% to about 10%, and most preferably from about 4% to about 7% of the fabric softening component. The concentrated version of the product contains from about 13% to about 40%, preferably from about 13% to 30%, and most preferably from about 13% to about 20% of the fabric softening component.

When the fabric softening composition is transferred to a flexible substrate according to the article of the present invention, the fabric softening agent (A) includes conventionally used cationic and nonionic fabric softening agents such as those listed in sections (1) to (5) and (i) to (vi) above.

The amount of fabric softening composition on the sheet is subject to normal coating parameters, such as the viscosity and melting point of the fabric softening components, and is typically from about 0.5 g to about 5 g, preferably from about 1 g to about 3.5 g. The fabric softening composition used in the present invention contains at least 1% up to about 95% of the fabric softening component. To achieve optimum softening effect at minimal cost, preferably from about 10% to about 80%, and most preferably from about 30% to about 70%, of the fabric softening component is used herein.

The quaternary ammonium salt is typically used in the amount of from about 10% to about 80%, preferably from about 30% to about 70%.

Silicone

The second essential ingredient of the fabric softening composition used in the present invention is a compatible organosilicone.

The organosilicones (also referred to herein as compatible silicones) used in the present invention are capable of forming compatible blends with the fabric softeners listed above.

The organosilicone used herein has a CH₂ percent content of about 25% to about 90%. The CH₂ percent content is defined as

% CH₂ = number of methylene (CH₂) groups/number of methylene groups and methyl groups × 100%

The organosilicones contained in the fabric conditioning composition according to the invention contain at least one unit of the formula A:

where m is a number from 0 to 2 and R is a monovalent hydrocarbon radical.

The value of (3-m)/2 in formula A means the ratio of oxygen atoms to silicon atoms, i.e. SiO1/2 means that one oxygen is shared between two silicon atoms.

R¹ in formula A is selected from the group consisting of:

(i) One unit of formula A1

where a is a number having a value of at least 1, preferably 3, b is a number from 0 to 10, preferably 1, R²

wherein R³ is a hydrocarbon radical having 4 to 40 carbon atoms, preferably 8 to 18 carbon atoms, and can be saturated, unsaturated, cyclic, acyclic, alkyl or aromatic; and R⁴ is hydrogen or a hydrocarbon radical having 1 to 40 carbon atoms, preferably hydrogen, and

(ii) a unit of formula A2

wherein R⁵ and R⁶ are independently selected from hydrogen or a hydrocarbyl radical having 1 to 45 carbon atoms which may be saturated, unsaturated, cyclic, acyclic, alkyl or aromatic, and at least one of R⁵ and R⁶ is a hydrocarbyl radical having 6 to 45 carbon atoms, wherein R⁷ is

wherein R⁸ is a divalent organic radical having 1 to 12 carbon atoms, which may be saturated, unsaturated, cyclic, acyclic, alkyl or aromatic, and which is preferably -CH₂CH₂CH₂-O-CH₂.

Therefore, organosilicones used in the present invention include alkylaminosilicones which satisfy the structural parameters described above and which have a methylene percent (% CH₂) of from about 25% to about 90%. The compatibility of the organosilicones herein with fabric softening agents depends, in part, on the CH₂ percent of the organosilicones. The preferred range of CH₂ percent for the silicones herein is from about 40% to about 90%, more preferably from about 50% to about 85%, and especially preferably from about 50% to about 75%, in order to increase the degree of compatibility of mixtures containing relatively large amounts of silicone.

The organosilicones contained in the compositions herein may be linear, branched or partially crosslinked, preferably linear, and may range from fluids, liquids or viscous liquids, gums and solids.

An example of a suitable alkylaminosilicone containing the unit of formula A1 is as follows:

An example of an alkylaminosilicone containing the unit of formula A2 is as follows:

Alkylaminosilicones used in this invention can be prepared by

(1) Treating silicones containing primary or secondary amine functional groups with epoxides, such as ethylene oxide, to form alkylaminosilicones having the unit of formula A1, or

(2) by treating epoxysilicones with primary or secondary amines, such as dicocoamine, to form alkylaminosilicones having the moiety of formula A2.

The modified alkylaminosilicones of the invention, which have the unit of formula A1, can be prepared by mixing epoxide compounds with aminosilicones in a pressure reactor and heating for about 24 hours, after which the unreacted epoxy compound is stripped off in vacuo. The amount of epoxy to be used is calculated based on the number of amine functional groups on the alkylaminosilicone. Preferably, two epoxides for each primary amine and one epoxide for each secondary amine are reacted to convert them to tertiary amines. A stoichiometric amount, or up to 25% excess, of the epoxy can be used. The reaction is preferably carried out at temperatures between 25°C and 150°C, especially between 50°C and 100°C. The pressure is preferably maintained at values in the range of 3.447 x 10⁵ Nm⁻² (50 psi) to 2.068 x 10⁶ Nm⁻² (300 psi), particularly 3.447 x 10⁵ Nm⁻² (50 psi) to 1.034 x 10⁶ Nm⁻² (150 psi). Typical aminosilicone starting compounds would include Dow Corning Q2-8075. The manner of preparation of the alkylaminosilicones having the unit of formula A1 is described in Examples 1 and 2 below and in US-A-499 459, Lin et al., entitled "Hydroxylhydrocarbyl Modified Aminoalkyl Silicones", (filed December 6, 1989).

The modified alkylaminosilicones having the unit of formula A2 can be prepared by mixing epoxysilicones, secondary amines and a solvent such as isopropanol or toluene and heating the mixture at reflux for about 24 hours, after which the solvent is removed by distillation or vacuum stripping. The amount of The amount of amine used is calculated based on the number of epoxy functional groups on the epoxy silicone. Preferably, a secondary amine is reacted for each epoxy functional group to convert the amine to a tertiary amine. A stoichiometric amount or up to a 25% excess of amine may be used. The reaction is preferably carried out between 50°C and 150°C, especially between 75°C and 110°C. The reaction is preferably carried out at atmospheric pressure, but may be carried out in a pressure reactor with the pressure maintained at values in the range of 3.447 x 10⁵ Nm⁻² (50 psi) to 2.068 x 10⁶ Nm⁻² (300 psi).

The modified alkylaminosilicones used in this invention contain amine groups which may be quaternized with, for example, alkyl halide or methyl sulfate or protonated with a Lewis acid such as hydrochloric acid, acetic acid, citric acid, formic acid and the like.

The alkylaminosilicones used herein may contain, in addition to the units of formula A, secondary units selected from the group consisting of a unit of formula B1 and a unit of formula B2: Formula B1 Formula B2

wherein R¹¹ is a hydrocarbon radical having 1 to 40 carbon atoms, preferably CH₃; R⁹⁰ is a hydrocarbon radical having 1 to 3 carbon atoms; R¹⁰ is oxygen or alkylene having 1 to 8 carbon atoms, preferably propylene; c and d are numbers from 0 to 50, preferably 2 to 15; and y and z are numbers from 0 to 2.

Organosilicones preferred for use herein have a CH₂ percent content of from about 40% to about 90% and are alkylaminosilicones containing the moiety of the formula A1.

The amount of organosilicone used herein is usually in the range of about 0.1% to about 20%, and is preferably at least about 0.5% to about 2% to maximize the spreading of the fabric softener on the fabric surface, but could be higher in concentrated liquids. Preferably, when the organosilicone is deposited on a substrate, the amount used is in the range of 0.1% to 20%, more preferably at least 3% to 20%. The amount of organosilicone is controlled by the ratio at which the mutually soluble mixture of the fabric softening component and the organosilicone is formed.

The weight ratio of the organosilicone to the fabric softening component in the fabric conditioning compositions used herein is in the range of about 100:2 to about 1:100, preferably in the range of about 2:100 to about 20:100, but must be such that a compatible mixture can be formed.

Silicone/Plasticizer Compatibility Test (SSCT)

As described above, blends defined as compatible herein include both mutually soluble and mutually stable dispersible blends. The compatibility of the fabric conditioning blends herein depends on the structure and CH₂ percent of the organosilicone and the particular fabric softener used in the blend. SSCT provides a basis for selecting appropriate combinations of the fabric softening component and the organosilicone.

The test can be used to determine compatibility at a particular weight ratio of interest or to determine a minimum concentration of the silicone at which a compatible mixture of the silicone and the fabric softening component is formed.

The SSCT is performed as follows:

A 10 g sample of the fabric softener or combination of fabric softeners is placed in a clear glass flask fitted with a stirring mechanism such as a magnetic stirrer. If either the fabric softener or silicone is a solid at room temperature, it is melted before starting the test, with the test being conducted above the melting point of the fabric softener or silicone. The silicone of interest is slowly added to the flask with, conveniently, a Pasteur pipette while stirring. It is estimated that the weight of one drop represents about 1% silicone concentration so that the silicone is mixed with the fabric softener at 1% at a time. Therefore, the lowest concentration of silicone in the mixture is about 1%.

If the resulting mixture of fabric softener and silicone remains clear over the entire range of silicone tested, this indicates that the components of the mixture are mutually soluble, and thus compatible, over the concentration range tested. Clear mixtures are defined herein as mixtures that exhibit approximately 90% transmittance when measured with a visible light probe (1 centimeter path length) against a background of distilled water using a Brinkman PC800 Colormeter.

The mixture may also become cloudy, indicating that the silicone and fabric softener are not mutually soluble at the weight percent of the silicone. In this case, if the mixture becomes cloudy, the weight percent of silicone added to form the cloud is calculated. This number, referred to as compatibility α, then represents the weight percent of silicone to form a cloudy mixture. Cloudy samples are placed in an oven at 100°C for at least two hours, then cooled to room temperature and examined. Samples which have completely separated into clear layers are incompatible and not useful for the present invention. Samples which have a stable, dispersed maintain their condition, are compatible and therefore useful for the invention.

It is sufficient for practical applications to test the silicone concentration range up to about 30%. However, the entire range up to 100% of the silicone concentration can be tested if desired. If the entire range of silicone concentration is to be tested, the silicone is added until the mixture contains about 60% by weight of silicone. The silicone addition is then stopped and the test repeated by adding the fabric softener up to a 10 g sample of the silicone. In those samples that become hazy, the weight percent of the plasticizer added to form the haze is calculated and subtracted from 100 and the number obtained is referred to herein as the compatibility β.

The α-compatibility reflects the compatibility of the blends containing a fabric softener as the main component, whereas the β-compatibility reflects the compatibility of the blends containing a silicone as the main component. The minimal difference between β and α (β-α) reflects the degree of compatibility of the blend: more compatible blends have a lower number for (β-α).

Preferably, silicone and fabric softening component are compatible at a silicone concentration of at least about 2%.

Mutually soluble and clear mixtures of the silicone and the fabric softening component indicate the highest degree of compatibility and are preferred.

Various additives may be used in combination with the compatible blend of fabric softening component and the compatible silicone. The additives are used in amounts which do not significantly affect the compatibility of the blend and include small amounts of incompatible silicones such as predominantly linear polydialkylsiloxanes, e.g. polydimethylsiloxanes; soil-releasing polymers such as block copolymers of polyethylene oxide and terephthalate; fatty amines selected from the group consisting of primary fatty amines, secondary fatty amines, tertiary fatty amines, and mixtures thereof; amphoteric surfactants; smectite-type inorganic clays; anionic soaps, zwitterionic quaternary ammonium compounds; and nonionic surfactants.

Other possible ingredients include emulsifiers, electrolytes, optical brighteners or fluorescent agents, buffers, perfumes, dyes, germicides and bactericides.

The fabric conditioning compositions of the invention can be used in the rinse cycle of a conventional household laundry cycle. Typically, rinse water has a temperature of from about 5°C to about 70°C. The concentration of total active ingredients is typically from about 2 ppm to about 1000 ppm, preferably from about 10 ppm to about 500 ppm, based on the weight of the aqueous rinse bath. If multiple rinses are used, the fabric softening composition is preferably added in the final rinse.

However, in accordance with a primary aspect of the invention, an article for conditioning fabrics in a tumble dryer is described. The article of the invention includes a flexible substrate carrying a fabric conditioning amount of a conditioning composition and capable of releasing the conditioning composition at dryer operating temperatures. The conditioning composition, in turn, has a preferred melting (or softening) point of from about 25°C to about 150°C.

The fabric conditioning composition used in the invention is coated on a dispensing device which effectively releases the fabric conditioning composition in a tumble dryer. Such dispensing devices can be designed for a single application or for multiple applications. Such an article contains a sponge material which releasably contains enough of the conditioning composition to effectively impart fabric softening during multiple drying cycles. This multi-purpose article can by filling a porous sponge with the composition. In use, the composition melts and leaches through the pores of the sponge to soften and condition the fabrics. Such a filled sponge can be used to treat multiple loads of fabrics in conventional dryers and has the advantage that it can be left in the dryer after use and is unlikely to be misplaced or lost.

Another article comprises a cloth or paper bag, releasably containing the composition and tightly closed with a hardened plug of the mixture. The behavior function and the heat of the dryer opens the bag and releases the composition to effect its softening.

A highly preferred article comprises the compositions containing a plasticizer and a compatible organosilicone releasably attached to a flexible substrate, such as a sheet of paper or fabric or nonwoven cloth substrate. When such an article is placed in an automatic clothes dryer, the heat, moisture, dispersal forces and tumbling action of the dryer remove the composition from the substrate and deposit it on the fabrics.

The sheet conformation has several advantages. For example, effective amounts of the compositions for use in conventional dryers can be easily absorbed onto and into the sheet substrate by a simple dipping or padding process. Therefore, the end user does not need to measure the amount of composition necessary to achieve fabric softness and other benefits. In addition, the flat shape of the sheet provides a large surface area, which results in effective release and distribution of the materials onto the fabrics by the tumbling action of the dryer.

The substrates used in the articles have a dense, or more preferably, open or porous structure. Examples of suitable materials used as substrates herein include paper, woven cloth and nonwoven cloth. The term "cloth" as used herein means a woven or nonwoven substrate for the articles of manufacture, as distinguished from the term "fabric" which includes the clothing fabrics dried in an automatic dryer.

It is known that most substances are capable of absorbing a liquid substance to some extent; however, the term "absorbent" as used herein is intended to mean a substrate having an absorbency (i.e., a parameter which means the ability of substrates to absorb and retain a liquid) of 4 to 12 times, preferably 5 to 7 times, its weight in water.

When the substrate is a foamed plastic material, the absorbency is preferably in the range of 15 to 22, however some special foams may have an absorbency in the range of 4 to 12.

The determination of the absorbance values is carried out using the capacity test procedure described in the U.S. Federal Specification (UU-T-595b) modified as follows:

1. Tap water is used instead of distilled water ;

2. the sample is immersed for 30 seconds instead of 3 minutes ;

3. the drainage time is 15 seconds instead of 1 minute; and

4. the sample is weighed directly on a torsion balance, which has a weighing pan with upwardly turned edges.

The absorbency values are then calculated according to the formula given in the above specification. Based on this test, a single ply, compact bleached paper [e.g. kraft or foolscap paper with a basis weight of about 14.52 kg (32 pounds) per Commercially available single-ply household paper towels (e.g., 2,787 × 10² m² (3000 square feet)) have an absorbency of 3.5 to 4; commercially available single-ply household paper towels have a value of 5 to 6; and commercially available two-ply household paper towels have a value of 7 to about 9.5.

Suitable materials that can be used as a substrate in the present invention include, but are not limited to, sponges, paper, and woven and nonwoven cloth, all of which have the necessary absorbency requirements as defined above.

The preferred nonwoven fabric substrates can be defined as generally adhesively bonded fibrous or filamentary products having a woven or carded fiber structure (wherein the fiber strength suitably permits carding), or they can comprise fibrous mats in which the fibers or filaments are distributed randomly or in a random arrangement (i.e., an arrangement of fibers in a carded fabric in which partial orientation of the fibers is often present as well as completely random distribution orientation), or lying substantially in a row. The fibers or filaments can be natural fibers (e.g., wool, silk, jute, hemp, cotton, linen, sisal fiber, or ramie) or synthetic fibers (e.g., rayon, cellulose esters, polyvinyl derivatives, polyolefins, polyamides, or polyesters).

The preferred absorbent properties are particularly readily achieved with nonwoven fabrics and are provided merely by building up the thickness of the fabric, i.e. by adding a plurality of carded fabrics or mats to a thickness sufficient to obtain the necessary absorbent properties or by allowing sufficient thickness of the fibers to deposit on the screen. Any diameter or denier of fiber (generally up to about 10 denier) may be used inasmuch as it is the free space between each fiber which makes the thickness of the fabric directly related to the absorbent capacity of the fabric and which further makes the nonwoven fabric particularly suitable for impregnation with a composition by cross-linking or capillary action. Consequently, any thickness necessary to achieve the required absorption capacity can be used.

When the substrate for the composition is a nonwoven fabric made from fibers deposited randomly or in a random arrangement on the screen, the articles exhibit excellent strength in all directions and do not tend to tear or separate when used in the automatic clothes dryer.

Preferably, the nonwoven fabric is water-borne or air-borne and made from cellulosic fibers, particularly regenerated cellulose or rayon. Such a nonwoven fabric may be fused with any of the usual textile lubricants. Preferably, the fibers are from 5 mm to 50 mm long and from 1.5 to 5 denier. Preferably, the fibers are at least partially randomly oriented and are adhesively bonded together with a hydrophobic or substantially hydrophobic binder resin. Preferably, the fabric contains about 70 weight percent fiber and 30 weight percent binder resin polymer and has a basis weight of about 18 to 45 grams per square meter.

When applying the fabric conditioning composition to the absorbent substrate, the amount impregnated into the absorbent substrate and/or onto the absorbent substrate is suitably in the weight ratio range of about 10:1 to 0.5:1 based on the ratio of the total conditioning composition to the dry, untreated substrate (fiber plus binder). Preferably, the amount of the conditioning composition is in the range of about 5:1 to about 1:1, more preferably about 3:1 to 1:1, based on the weight of the dry, untreated substrate.

According to a preferred embodiment of the invention, the dry sheet substrate is coated by passing it over a gravure applicator roller. As it passes over this roller, the sheet is coated with a thin, uniform Layer of molten fabric softening composition contained in a rectangular pan at a level of about 17.94 g/m² (15 g/square yard). Passing the substrate over a chill roll then solidifies the molten softening composition into a solid. This type of applicator is used to achieve a uniform homogeneous coating across the sheet.

After application of the liquefied composition, the articles are maintained at room temperature until the composition has substantially solidified. The resulting dry articles, prepared at the proportions of the composition substrate set forth above, remain flexible; the sheet articles are suitable for packaging in rolls. The sheet articles may optionally be slit or pierced to provide a non-blocking side at any suitable time if desired during the manufacturing process.

The following examples will more fully illustrate the embodiment of this invention. All parts, percentages and ratios in this specification and in the following claims are by weight of the composition unless otherwise indicated.

Examples 1 to 6 include organosilicones within the scope of the present invention having the following formulas A, B, C and D: Formula A Formula B Formula C Formula D

example 1

The silicone of formula C is a reaction product of the starting aminosilicone, wherein the nitrogen-containing branched chain is -(CH2)3-NH-(CH2)2NH2) and 1,2-epoxyoctadecane. The compound was prepared by placing the starting aminosilicone (61.16 g), 1,2-epoxyoctadecane (38.84 g) and 2-propanol (60.0 g) in a reaction vessel by heating at 80°C for a period of 24 hours. The reaction vessel consisted of a three-necked round bottom flask containing a stirrer, reflux condenser and thermometer. The 2-propanol was then stripped by N2 bubbling at 100°C as described in the above-mentioned Lin et al. application. described.

The silicone of formula C has a CH₂ percentage of 56.62.

Example 2

A "T" structure modified alkylaminosilicone of formula D having a CH₂ percent content of 52.50 was prepared. In the starting aminosilicone, the nitrogen-containing chain branch had the formula -(CH₂)₃-NH-(CH₂)₂NH₂. In the modified aminosilicone, the hydrogens on the nitrogen atoms were replaced by the following formula

In the process, 34.7 g of the starting aminosilicone, 34.4 g of 1,2-epoxydodecane and 17.4 g of 2-propanol were charged into the reaction vessel according to the procedure of Example 1.

Example 3

The effect of CH₂ percent of various silicones as given in Table I on compatibility with Adogen 442 (dihydrogenated tallow dimethyl ammonium chloride from Sherex Corp.) was investigated by mixing the silicones with Adogen 442 according to the SSCT procedure.

The results obtained are summarized in Table I. Samples 6 and 7 were synthesized in Examples 1 and 2, respectively. Table I Silicone CH₂ Percent Compatible Formula Formula B, protonated No Yes * Linear polydimethylsiloxane supplied by Dow Corning, viscosity = 1 × 10⁻³ m²s⁻¹ (1000 cSt) ** Aminosilicone supplied by Dow Corning, amine neutral equivalent = 2000, viscosity = 1.3 × 10⁻⁴ m²s⁻¹ (130 cSt).

The silicones of Examples 3 to 7 were mutually soluble with Adogen 442 at a silicone concentration of 5% by weight of the mixture. However, Silicones 1 and 2, which are not within the scope of the present invention, were not compatible with Adogen 442 at 5% or even at 25% silicone.

Examples 4 to 6 Contact angle measurements

Contact angle values reflect the spreading behavior of a liquid on a solid surface. The discussion of the relationship between contact angle values and the spreading is given, for example, in Chapter 6 of "Introduction to Colloid and Surface Chemistry", Duncan J. Shaw, Butterworth, 1985. A contact angle of a liquid on a solid surface is the angle between the tangent of the droplet and the surface. A smaller contact angle indicates better spreading on the surface. When it is desired to measure the contact angle on tissues, there is an experimental problem of accurately measuring the exact contact angle: Due to the surface roughness of the tissue, it is difficult to obtain an accurate baseline. Therefore, accurate contact angle measurements are obtained using cellulose paper.

Samples were prepared by mixing a fabric softener and a silicone above the melting point. A droplet of the melted liquid was deposited on a piece of cellulose filter paper. After the droplet cooled and solidified, an initial contact angle was measured. The cellulose paper with the droplet was then placed in an oven at 70ºC for 30 minutes to obtain the equilibrium contact angle. The paper was then removed from the oven and a final contact angle was measured.

The contact angle was measured using a contact angle goniometer (Rame-Hart Model 100). The cellulose containing the active drop was placed on a slide and examined with a microscope. With the light source on, the drop appeared as a silhouette against a soft green background. The drop/cellulose interface was aligned with the horizontal crosshair and the contact angle was determined by rotating the read crosshair until it touched the right profile of the drop. The contact angle value was then read directly from the goniometer scale, which was graduated in degrees. This procedure was repeated to read the contact angle on the left side. Both sides should give the same reading, otherwise the sample was not correctly leveled and the step height should be readjusted.

Example 4

The effect of various silicones listed in Table II on the spreading of Adogen 442 was studied. The true contact angle (at the beginning and at the end) of the blends of silicones and Adogen 442 prepared in Example 3 was measured on cellulose paper as described above. In addition, the spreading of the blends on cotton fabric was qualitatively evaluated using a score of 1 to 4: 1 = best spreading, 2 = moderate spreading, 3 = droplets begin to wet the surface, 4 = no spreading, droplets bead off. Sample 1 contained only Adogen 442 without any silicone and was used as a control.

The results obtained are summarized in Table II below. Table II Sample No. Silicone Cotton Cellulose Start End None Formula Formula B, protonated

Initial and final contact angles for Samples 4 to 8 containing compatible silicones within the scope of the invention were lower than contact angles for Samples 1 to 3. The silicones of Samples 4 to 8 are shown to be mutually soluble mixtures with Adogen 442 in Example 3 form.

Samples 1 through 3 contained either no silicone or silicones that are not within the scope of the invention. The results showed that in mutually soluble blends of compatible silicones and fabric softener according to the present invention, compatible silicones improve the spreading of the fabric softener on a cellulosic surface. Qualitative evaluation of spreading on cotton showed the same pattern of improved spreading when compatible silicones were used within the scope of the invention.

Example 5

The concentration effect of various silicones, as indicated in Table III, on the spreading of Adogen 442 fabric softener was investigated by measuring the contact angle at a cellulose surface using the procedure described above. Table III Sample No. Silicone Final Contact Angle at Silicone Percent of Formula B Formula D, protonated

This example shows that in Samples 2 to 5 containing organosilicone within the scope of the invention, as little as about 2 weight percent of the mixture is necessary to reduce the contact angle to improve spreading on the surface.

A further increase in the silicone concentration in samples 2 to 5 further reduces the contact angle, indicating even better spreading on the surface.

The silicone of Sample 1, which is not suitable for the present invention, does not reduce the contact angle of the fabric softener regardless of the amount of silicone used.

Example 6

Blends of various silicones, as indicated in Table IV, with non-ionic fabric softeners, such as mineral oil, were tested. Spreading of the blends on cotton and polycotton fabrics was tested by measuring the fabric area (cm2) per gram of mineral oil spread on the fabrics.

All samples contained 5% by weight of a silicone blend. The mineral oil used was Semtol 350 from Witco Corp. Table IV Sample No. Silicone Viscosity (m²s⊃min;¹/cSt) Surface Tension (dyn/cm) Fabric Area Cotton Polycotton None Formula

The silicone of formula B was only partially soluble in mineral oil, whereas the silicone of formula D formed a mutually soluble mixture with mineral oil, which demonstrated that the mutual solubility of the silicones and the fabric softeners depends on the particular fabric softener as well as on the CH₂ percentage of the silicone.

Silicones B and D both reduced the surface tension of the mineral oil, as was observed in the absence of silicones in Example 1. However, the tissue surface area was increased only in Example 3, where a mutually soluble mixture was formed.

Examples 7 to 8

Examples 7 to 8 include organosilicones, both outside and within the scope of the invention, having the formulas E, F and G below. Formula E (comparative example) Formula F Formula G (comparative example

Example 7

The mutual solubility of organosilicones with fabric softening agent mixtures was investigated in the following formulations: Formulation No. Fabric softening component blend 10% Varisoft 475 10% Mineral oil 10% Adogen 442 1% Myristic acid 11.7% Varisoft 445** 3.5% Stearic acid * Varisoft 475 = Methyl-1-tallowamidoethyl-2-tallowimidazolinium methylsulfate ** Varisoft 445 = Methyl-1-hydrogenated tallowamidoethyl-2-tallowimidazolinium methylsulfate

The fabric softening blends of Formulations I, II and III above were heated and melted at approximately 80ºC. Various silicones as indicated in Table V below were added with stirring until the resulting blend became cloudy. At this point, the The percentage of silicone added was recorded as the solubility of the silicone in the formulation. The results obtained are given in Table V below. Table V Formulation No. Silicone solubility (%) Silicone E Silicone F (comparative) * PDMS = polydimethylsiloxane, viscosity = 1 × 10⊃min;2 m2s⊃min;1 (10 000 cSt)

Silicone F was significantly more soluble in Formulations I, II and III than PDMS.

Example 8 (comparison)

Various silicones, both outside and within the scope of the present invention, as set forth in Table VI, were incorporated into liquid fabric conditioning compositions. Fabric softeners and silicones were mixed together at 80°C (above melting point) and then dispersed in water at 60°C to 80°C to form liquid compositions containing composite particles of the fabric softening component and the silicone.

The resulting compositions are summarized in Table VI below. Table VI Ingredients Sample Adogen Varisoft Neodol* Siponic L7-90** Mineral oil Myristic acid Stearic acid Silicone E (comparative) Silicone G (comparative) Silicone F Water * Neodol 23 = Lauryl alcohol ** Siponic L-7-90 = C₁₂H₂₅-(OCH₂CH₂)₁₂OH, ex Alcolac

Samples C, D, E, G and H were further tested for their softening properties. Terry cloth fabrics were prewashed with a solution of Neodol 25-9 (alcohol ethoxylate from Shell Corp.) and Na₂CO₃ to remove textile finishes on the surface, rinsed with the samples in a tergometer and then line dried. The cloth load was 20 g per liter and the active concentration was 0.1 g per liter of rinse liquid. The control was rinsed with water only. Using a pairwise comparison, a panel of 20 people determined the softness of the treated cloth versus the control. All experts preferred the treated cloth over the control in all tests.

Examples 9 to 11 (comparison)

The compatibility of various tissue softeners with various silicones was determined by SSCT. The entire concentration range up to 100% of the silicones was investigated. Samples that remained clear over the entire range of silicone concentrations were designated as "fully soluble". For samples that became cloudy, the stability of the dispersions was determined and α and β compatibility values were determined by SSCT.

The silicones that were tested are listed in Table II. In the silicone formulas of Table II.

M = Me₂SiO0.5'

D = Me₂Si-O, D* = Me- iR' and R' have the meaning given in Table II. Table II Code Formula CH₂ Percent Polydimethylsiloxane (= 1 × 10⁻³ m²s⁻¹ (1000 cSt)) * Code CC, Formula MD100D*5M is equivalent to Formula G of Example 8.

Example 9

In this example, blends of the silicones shown in Table II with mineral oil were tested using SSCT. The mineral oil used was "Fished Light Mineral Oil". The results obtained are summarized in Table III below. Table III Compatibility with mineral oil Silicone Compatibility Compatible (Yes/No) Completely soluble No Yes

As determined by SSCT, the silicones CC, EE and FF listed by the present invention form compatible blends with mineral oil with the structural conditions and CH₂ percent.

Example 10

In this example, blends of the silicones listed in Table II with various cationic quaternary fabric softeners were tested using the SSCT.

The results obtained are summarized in Tables IV, V and VI. Table IV Compatibility with Varisoft 137* Silicone Compatibility Compatible (Yes/No) No Yes * Varisoft 137 = Di-(hydrogenated)tallow dimethylammonium methyl sulfate from Sherex. Table V Compatibility with Varisoft 445* Silicone Compatibility Compatible (Yes/No) No Yes * Varisoft 445 = Di-(hydrogenated)tallowimidazolinium methylsulfate from Sherex. Table VI Compatibility with Varisoft 110* Silicone Compatibility Compatible (Yes/No) No Yes *Varisoft 110 = Methyl bis(hydrogenated tallow aminoethyl) 2-hydroxyethylammonium methyl sulfate from Sherex.

Example 11

In this example, blends of the silicones listed in Table II with various nonionic fabric softeners are tested using the SSCT.

The results obtained are summarized in Tables VII, VIII, IX and X below. Table VII Compatibility with Neodol 45-7* Silicone Compatibility Compatible (Yes/No) No Yes * Neodol 45-7 = Ethoxylated fatty alcohol from Shell. Table VIII Compatibility with Adogen 345D* Silicone Compatibility Compatible (Yes/No) Completely soluble No Yes * Adogen 345D = Di-(hydrogenated)tallow dimethylamine from Sherex. Table IX Compatibility with PEG 600* Silicone Compatibility Compatible (Yes/No) Completely soluble No Yes * PEG 600 = Polyethylene glycol Table X Compatibility with isostearic acid Silicone Compatibility Compatible (Yes/No) No Yes

Examples 3-6 demonstrate that mutual compatibility between the fabric softening component and the organosilicones can be readily determined by the SSCT and that compatibility depends on the structure and CH2 percent of the silicone as well as the particular fabric softening component used in the blend. Although Silicone C was highly compatible (mutually soluble) with mineral oil in Example 3 and with Adogen 345D in Example 6, there was less compatibility with Varisoft 137 of Example 4, i.e., a cloudy blend was formed at 2% silicone. However, Silicone C was more compatible with Varisoft 137 in Example 4 than polydimethylsiloxane because the β-compatibility for Silicone C was lower than for polydimethylsiloxane. The results in Table VIII show that amines have the highest degree of compatibility with organosilicones, since Silicone B, which has a CH2 percent of 14% and is not within the scope of this invention, is still compatible with di(hydrogenated)tallow dimethylamine. Silicones E and F, which have a high CH2 percent (43% and 57% respectively), were the ones that were most compatible with all plasticizers tested.

Example 12 (Comparison)

Two tissue softening sheets, A and B, were prepared as follows.

The ingredients of a fabric conditioning composition as indicated below were melt blended. 500 g of the fabric conditioning blend prepared was placed in the receiver of a two-roll applicator and applied to a spunbonded polyester nonwoven material. The fabric softening articles thus prepared contained about 1.6 g of the solidified softening composition. The articles of manufacture were then placed in a tumble dryer machine already containing 2.2 kg of pre-laundered clothing including terry cloth softness controller. The fabrics were then tumble dried with the fabric softening article until dry and the softening benefit was evaluated by a panel of 20 experts.

Tissue Conditioning Formulation for Sheet A:

(a) 10% of a silicone not suitable for use in the present invention (Silicone BB from Table II);

(b) 70% di(hydrogenated)tallow dimethylammonium methyl sulfate;

(c) 20% stearic acid. Fabric Conditioning Formulation for Sheet B:

(a) 7% Silicone FF from Table II;

(b) 70% di(hydrogenated)tallow dimethylammonium methyl sulfate;

(c) 23% stearic acid.

Observations and results:

Sheet A - Due to the incompatible nature of the silicone, the silicone had separated from the emollient component during the coating process. The articles therefore contained unknown amounts of the silicone.

Sheet B - The compatible Silicone FF and the plasticizer component formed a compatible mixture which remained homogeneous during the coating process as it was transferred to the substrate, indicating that the substrate was coated uniformly and evenly.

A panel of 20 experts evaluated the Towel Monitors for both Sheet A and Sheet B for superior softness to towels manufactured in an identical manner but dried without softener.

Claims (11)

1. A fabric conditioning article providing for the release of a fabric conditioning composition within an automatic clothes dryer at dryer operating temperatures, the article including a flexible substrate bearing thereon discrete composite particles consisting of a compatible mixture of: (a) at least 1% of a fabric softening component, including a cationic quaternary ammonium salt, and (b) an organosilicone having a CH₂ percentage content of from 25% to 90% and containing at least one unit of formula A: where m is a number with a value from 0 to 2, R is a monovalent hydrocarbon radical and R¹ (i) a unit of formula A1 wherein a is a number having a value of at least 1, b is a number from 0 to 10, R² wherein R is a hydrocarbon radical having 4 to 40 carbon atoms and R⁴ is hydrogen or a hydrocarbon radical having 1 to 40 carbon atoms, or (ii) a unit of formula A2 wherein R⁵ and R⁶, independently, are selected from hydrogen or a hydrocarbon radical having 1 to 45 carbon atoms. and at least one of R⁵ and R⁶ is a hydrocarbon radical having 6 to 45 carbon atoms, wherein R⁷ is wherein R⁸ is a divalent organic radical having 1 to 12 carbon atoms. 2. An article according to claim 1, characterized in that the CH₂ percentage content of the organosilicon (b) is 40% to 90%. 3. An article according to any one of the preceding claims, characterized in that the composite particles consist of a mutually soluble mixture which, once in liquefied form, provides a clear homogeneous liquid. 4. An article according to any preceding claim, characterized in that R¹ contains from 8 to 18 carbon atoms. 5. An article according to any one of the preceding claims, characterized in that a has a value of 3 and b has a value of 1. 6. An article according to any preceding claim, characterized in that R³ contains from 8 to 18 carbon atoms. 7. An article according to any preceding claim, characterized in that R⁴ is hydrogen . 8. An article according to any one of the preceding claims, characterized in that m has the value 1 . 9. An article according to any one of the preceding claims, characterized in that the amount of organosilicon (b) is in the range of 0.1 to 20% by weight of the particles. 10. An article according to claim 9, characterized in that the amount of organosilicone (b) in the range of 3 to 20 percent by weight of the particles. 11. An article according to any preceding claim, characterized in that the flexible substrate is in a sheet configuration.